The present invention, in general, relates to reference oscillators for supplying periodic output signals and, more articularly, to a method and oscillator system for providing accurate output pulses for use in fixed frequency systems for example.
Fixed frequency Switching Mode Power Supply (SMPS) systems contain an oscillator subsystem that drives the system with an accurate periodic output signal. The accuracy of the oscillator dictates the performance of the whole SMPS system. Typically, prior art oscillator subsystems, in order to obtain oscillator accuracy requirements, have been very complex requiring high component count and die area when manufactured in monolithic integrated circuit form. The foregoing is directly proportional to the system costs. Additionally, these controller oscillator systems are responsive to an internally generated saw tooth signal that charges and discharges between high and low voltage references. The accuracy of the oscillator output signal is therefore a function of the accuracy of these two voltage references over temperature and circuit process variations.
Hence, a need exists for a relatively inexpensive oscillator subsystem while maintaining accurate system parameters.